Identify function: Identify the function to differentiate.We are given the function y=−(x+7)2−9, and we need to find its derivative with respect to x.
Apply chain rule: Apply the chain rule for differentiation.The chain rule states that the derivative of a composite function is the derivative of the outer function evaluated at the inner function times the derivative of the inner function. In this case, the outer function is −u2 and the inner function is u=x+7.
Differentiate outer function: Differentiate the outer function with respect to the inner function u. The outer function is −u2. Its derivative with respect to u is −2u.
Differentiate inner function: Differentiate the inner function with respect to x. The inner function is u=x+7. Its derivative with respect to x is 1, since the derivative of x is 1 and the derivative of a constant is 0.
Apply chain rule multiplication: Apply the chain rule by multiplying the derivatives from Step 3 and Step 4.The derivative of y with respect to x is the product of the derivative of the outer function and the derivative of the inner function: dxdy=−2u×1.
Substitute inner function: Substitute the inner function back into the derivative.Replace u with x+7 in the derivative we found in Step 5: dxdy=−2(x+7).
Simplify derivative: Simplify the derivative.The derivative simplifies to dxdy=−2x−14.
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